Three-dimensional computer-generated animation typically is created by defining a scene with one or more objects. An object may be defined in a number of ways, such as using a skeleton and associated mesh, NURBS surfaces, particles and the like. The position, orientation, scale and/or other properties of each object may be animated over time. The surface of each object also may be textured through a process called shading or rendering to make the object appear realistic. The complexity of a scene may vary depending on the number of objects, the complexity of each object and the complexity of the animation. Input scene data of a variety of different types is processed, using a number of different operations, to edit three-dimensional content or to produce a two-dimensional image (or sequence of such images) representing a view of the three-dimensional scene.
Most systems for authoring three-dimensional computer-generated animation represent the combination of operations defining a scene using a form of operator graph. Each node in an operator graph represents an operation on data. Operators may vary any parameter that defines the scene. A node can represent an operation that is implemented as an explicitly coded function of a computer program or can represent an operation that is defined by another operator graph.
These operator graphs are designed to enable the scene to be created using a variety of types of three-dimensional data, including, but not limited to, NURBS surfaces, meshes, particles, skeletons, properties, constraints, etc. In other words, each operator may operate on different kind of data than other operators. Some operators are more complex than others. For example, some operators may perform simple deformations, whereas others may define complex constraints between three-dimensional data. Thus, operator graphs can be characterized as heterogeneous. As a result, each operation in the operator graph is typically performed independently of the others; however, each operation is typically implemented to exploit any parallelism that is possible for that operation.
Accordingly, the processing resources required to display animation are significant. There are different needs, however, for interactive editing than for playback. In particular, editing tools represent data in more flexible ways that allow interactive changes that modify the operator graph, such as adding, removing and/or modifying geometrical elements, whereas playback caches and optimizes data in memory to allow fast read access by viewing processes and may involve compiling the operator graph for efficient playback. As a result, editing tools and playback systems arrange data in memory and process an operator graph differently.
Developments in computer architectures are resulting in more powerful computers with many processors, including one or more central processing units (CPU), and/or one or more graphics processing units (GPU), and/or one or more physics processing units (PPU) and/or one or more cell processors (a multi-core CPU). While these processing resources improve the capability of a system to support interactive editing or playback, it is a challenge to use these resources efficiently.